= Action Web Service -- Serving APIs on rails
Action Web Service provides a way to publish interoperable web service APIs with
Rails without spending a lot of time delving into protocol details.
== Features
* SOAP RPC protocol support
* Dynamic WSDL generation for APIs
* XML-RPC protocol support
* Clients that use the same API definitions as the server for
easy interoperability with other Action Web Service based applications
* Type signature hints to improve interoperability with static languages
* Active Record model class support in signatures
== Defining your APIs
You specify the methods you want to make available as API methods in an
ActionWebService::API::Base derivative, and then specify this API
definition class wherever you want to use that API.
The implementation of the methods is done separately from the API
specification.
==== Method name inflection
Action Web Service will camelcase the method names according to Rails Inflector
rules for the API visible to public callers. What this means, for example,
is that the method names in generated WSDL will be camelcased, and callers will
have to supply the camelcased name in their requests for the request to
succeed.
If you do not desire this behaviour, you can turn it off with the
ActionWebService::API::Base +inflect_names+ option.
==== Inflection examples
:add => Add
:find_all => FindAll
==== Disabling inflection
class PersonAPI < ActionWebService::API::Base
inflect_names false
end
==== API definition example
class PersonAPI < ActionWebService::API::Base
api_method :add, :expects => [:string, :string, :bool], :returns => [:int]
api_method :remove, :expects => [:int], :returns => [:bool]
end
==== API usage example
class PersonController < ActionController::Base
web_service_api PersonAPI
def add
end
def remove
end
end
== Publishing your APIs
Action Web Service uses Action Pack to process protocol requests. There are two
modes of dispatching protocol requests, _Direct_, and _Delegated_.
=== Direct dispatching
This is the default mode. In this mode, public controller instance methods
implement the API methods, and parameters are passed through to the methods in
accordance with the API specification.
The return value of the method is sent back as the return value to the
caller.
In this mode, a special <tt>api</tt> action is generated in the target
controller to unwrap the protocol request, forward it on to the relevant method
and send back the wrapped return value. <em>This action must not be
overridden.</em>
==== Direct dispatching example
class PersonController < ApplicationController
web_service_api PersonAPI
def add
end
def remove
end
end
class PersonAPI < ActionWebService::API::Base
...
end
For this example, protocol requests for +Add+ and +Remove+ methods sent to
<tt>/person/api</tt> will be routed to the controller methods +add+ and +remove+.
=== Delegated dispatching
This mode can be turned on by setting the +web_service_dispatching_mode+ option
in a controller to <tt>:delegated</tt>.
In this mode, the controller contains one or more web service objects (objects
that implement an ActionWebService::API::Base definition). These web service
objects are each mapped onto one controller action only.
==== Delegated dispatching example
class ApiController < ApplicationController
web_service_dispatching_mode :delegated
web_service :person, PersonService.new
end
class PersonService < ActionWebService::Base
web_service_api PersonAPI
def add
end
def remove
end
end
class PersonAPI < ActionWebService::API::Base
...
end
For this example, all protocol requests for +PersonService+ are
sent to the <tt>/api/person</tt> action.
The <tt>/api/person</tt> action is generated when the +web_service+
method is called. <em>This action must not be overridden.</em>
Other controller actions (actions that aren't the target of a +web_service+ call)
are ignored for ActionWebService purposes, and can do normal action tasks.
=== Layered dispatching
This mode can be turned on by setting the +web_service_dispatching_mode+ option
in a controller to <tt>:layered</tt>.
This mode is similar to _delegated_ mode, in that multiple web service objects
can be attached to one controller, however, all protocol requests are sent to a
single endpoint.
Use this mode when you want to share code between XML-RPC and SOAP clients,
for APIs where the XML-RPC method names have prefixes. An example of such
a method name would be <tt>blogger.newPost</tt>.
==== Layered dispatching example
class ApiController < ApplicationController
web_service_dispatching_mode :layered
web_service :mt, MovableTypeService.new
web_service :blogger, BloggerService.new
web_service :metaWeblog, MetaWeblogService.new
end
class MovableTypeService < ActionWebService::Base
...
end
class BloggerService < ActionWebService::Base
...
end
class MetaWeblogService < ActionWebService::API::Base
...
end
For this example, an XML-RPC call for a method with a name like
<tt>mt.getCategories</tt> will be sent to the <tt>getCategories</tt>
method on the <tt>:mt</tt> service.
== Customizing WSDL generation
You can customize the names used for the SOAP bindings in the generated
WSDL by using the wsdl_service_name option in a controller:
class WsController < ApplicationController
wsdl_service_name 'MyApp'
end
You can also customize the namespace used in the generated WSDL for
custom types and message definition types:
class WsController < ApplicationController
wsdl_namespace 'http://my.company.com/app/wsapi'
end
The default namespace used is 'urn:ActionWebService', if you don't supply
one.
== ActionWebService and UTF-8
If you're going to be sending back strings containing non-ASCII UTF-8
characters using the <tt>:string</tt> data type, you need to make sure that
Ruby is using UTF-8 as the default encoding for its strings.
The default in Ruby is to use US-ASCII encoding for strings, which causes a string
validation check in the Ruby SOAP library to fail and your string to be sent
back as a Base-64 value, which may confuse clients that expected strings
because of the WSDL.
Two ways of setting the default string encoding are:
* Start Ruby using the <tt>-Ku</tt> command-line option to the Ruby executable
* Set the <tt>$KCODE</tt> flag in <tt>config/environment.rb</tt> to the
string <tt>'UTF8'</tt>
== Testing your APIs
=== Functional testing
You can perform testing of your APIs by creating a functional test for the
controller dispatching the API, and calling #invoke in the test case to
perform the invocation.
Example:
class PersonApiControllerTest < Test::Unit::TestCase
def setup
@controller = PersonController.new
@request = ActionController::TestRequest.new
@response = ActionController::TestResponse.new
end
def test_add
result = invoke :remove, 1
assert_equal true, result
end
end
This example invokes the API method <tt>test</tt>, defined on
the PersonController, and returns the result.
=== Scaffolding
You can also test your APIs with a web browser by attaching scaffolding
to the controller.
Example:
class PersonController
web_service_scaffold :invocation
end
This creates an action named <tt>invocation</tt> on the PersonController.
Navigating to this action lets you select the method to invoke, supply the parameters,
and view the result of the invocation.
== Using the client support
Action Web Service includes client classes that can use the same API
definition as the server. The advantage of this approach is that your client
will have the same support for Active Record and structured types as the
server, and can just use them directly, and rely on the marshaling to Do The
Right Thing.
*Note*: The client support is intended for communication between Ruby on Rails
applications that both use Action Web Service. It may work with other servers, but
that is not its intended use, and interoperability can't be guaranteed, especially
not for .NET web services.
Web services protocol specifications are complex, and Action Web Service client
support can only be guaranteed to work with a subset.
==== Factory created client example
class BlogManagerController < ApplicationController
web_client_api :blogger, :xmlrpc, 'http://url/to/blog/api/RPC2', :handler_name => 'blogger'
end
class SearchingController < ApplicationController
web_client_api :google, :soap, 'http://url/to/blog/api/beta', :service_name => 'GoogleSearch'
end
See ActionWebService::API::ActionController::ClassMethods for more details.
==== Manually created client example
class PersonAPI < ActionWebService::API::Base
api_method :find_all, :returns => [[Person]]
end
soap_client = ActionWebService::Client::Soap.new(PersonAPI, "http://...")
persons = soap_client.find_all
class BloggerAPI < ActionWebService::API::Base
inflect_names false
api_method :getRecentPosts, :returns => [[Blog::Post]]
end
blog = ActionWebService::Client::XmlRpc.new(BloggerAPI, "http://.../xmlrpc", :handler_name => "blogger")
posts = blog.getRecentPosts
See ActionWebService::Client::Soap and ActionWebService::Client::XmlRpc for more details.
== Dependencies
Action Web Service requires that the Action Pack and Active Record are either
available to be required immediately or are accessible as GEMs.
It also requires a version of Ruby that includes SOAP support in the standard
library. At least version 1.8.2 final (2004-12-25) of Ruby is recommended; this
is the version tested against.
== Download
The latest Action Web Service version can be downloaded from
http://rubyforge.org/projects/actionservice
== Installation
You can install Action Web Service with the following command.
% [sudo] ruby setup.rb
== License
Action Web Service is released under the MIT license.
== Support
The Ruby on Rails mailing list
Or, to contact the author, send mail to bitserf@gmail.com
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